Search results for: process issues

Authors: Sofia M. Karadimitriou, Kostas Triantafyllopoulos, Timothy Heaton

Abstract:

Reduced dimension Dynamic Spatio-Temporal Models (DSTMs) jointly describe the spatial and temporal evolution of a function observed subject to noise. A basic state space model is adopted for the discrete temporal variation, while a continuous autoregressive structure describes the continuous spatial evolution. Application of such a DSTM relies upon the pre-selection of a suitable reduced set of basic functions and this can present a challenge in practice. In this talk, we propose an online estimation method for high dimensional spatio-temporal data based upon DSTM and we attempt to resolve this issue by allowing the basis to adapt to the observed data. Specifically, we present a wavelet decomposition in order to obtain a parsimonious approximation of the spatial continuous process. This parsimony can be achieved by placing a Laplace prior distribution on the wavelet coefficients. The aim of using the Laplace prior, is to filter wavelet coefficients with low contribution, and thus achieve the dimension reduction with significant computation savings. We then propose a Hierarchical Bayesian State Space model, for the estimation of which we offer an appropriate particle filter algorithm. The proposed methodology is illustrated using real environmental data.

Keywords: multidimensional Laplace prior, particle filtering, spatio-temporal modelling, wavelets

Procedia PDF Downloads 422

Authors: Karen Trimmer, Raelene Ward, Linda Wondunna-Foley

Abstract:

Within Australian tertiary institutions, the subject of Aboriginal and Torres Strait Islander education has been a major concern for many years. Aboriginal and Torres Strait Islander teachers are significantly under-represented in Australian schools and universities. High attrition rates in teacher education and in the teaching industry have contributed to a minimal growth rate in the numbers of Aboriginal and Torres Strait Islander teachers in previous years. There was an increase of 500 Indigenous teachers between 2001 and 2008 but these numbers still only account for one percent of teaching staff in government schools who identified as Aboriginal and Torres Strait Islander Australians (Ministerial Council for Education, Early Childhood Development and Youth Affairs 2010). Aboriginal and Torres Strait Islander teachers are paramount in fostering student engagement and improving educational outcomes for Indigenous students. Increasing the numbers of Aboriginal and Torres Strait Islander teachers is also a key factor in enabling all students to develop understanding of and respect for Aboriginal and Torres Strait Islander histories, cultures, and language. An ambitious reform agenda to improve the recruitment and retention of Aboriginal and Torres Strait Islander teachers will be effective only through national collaborative action and co-investment by schools and school authorities, university schools of education, professional associations, and Indigenous leaders and community networks. Whilst the University of Southern Queensland currently attracts Indigenous students to its teacher education programs (61 students in 2013 with an average of 48 enrollments each year since 2010) there is significant attrition during pre-service training. The annual rate of exiting before graduation remains high at 22% in 2012 and was 39% for the previous two years. These participation and retention rates are consistent with other universities across Australia. Whilst aspirations for a growing number of Indigenous people to be trained as teachers is present, there is a significant loss of students during their pre-service training and within the first five years of employment as a teacher. These trends also reflect the situation where Aboriginal and Torres Strait Islander teachers are significantly under-represented, making up less than 1% of teachers in schools across Australia. Through a project conducted as part the nationally funded More Aboriginal and Torres Strait Islander Teachers Initiative (MATSITI) we aim to gain an insight into the reasons that impact Aboriginal and Torres Strait Islander student’s decisions to exit their program. Through the conduct of focus groups and interviews with two graduating cohorts of self-identified Aboriginal and Torres Strait Islander students, rich data has been gathered to gain an understanding of the barriers and enhancers to the completion of pre-service qualification and transition to teaching. Having a greater understanding of these reasons then allows the development of collaborative processes and procedures to increase retention and completion rates of new Indigenous teachers. Analysis of factors impacting on exit decisions and transitions has provided evidence to support change of practice, redesign and enhancement of relevant courses and development of policy/procedures to address identified issues.

Keywords: graduation, indigenous, pre-service teacher education, retention

Procedia PDF Downloads 463

Authors: Fadilah Aleanizy

Abstract:

Colicins are a family of bacterial toxins that kill Escherichia coli and other closely related species. The mode of action of colicins involves binding to an outer membrane receptor and translocation across the cell envelope, leading to cytotoxicity through specific targets. The mechanism of colicin cytotoxicity includes a non-specific endonuclease activity or depolarization of the cytoplasmic membrane by pore-forming activity. For Group A colicins, translocation requires an interaction between the N-terminal domain of the colicin and a series of membrane- bound and periplasmic proteins known as the Tol system (TolB, TolR, TolA, TolQ, and Pal and the active domain must be translocated through the outer membranes. Protein-protein interactions are intrinsic to virtually every cellular process. The transient protein-protein interactions of the colicin include the interaction with much more complicated assemblies during colicin translocation across the cellular membrane to its target. The potassium release assay detects variation in the K+ content of bacterial cells (K+in). This assays is used to measure the effect of pore-forming colicins such as ColA on an indicator organism by measuring the changes of the K+ concentration in the external medium (K+out ) that are caused by cell killing with a K+ selective electrode. One of the goals of this work is to employ a quantifiable in-vivo method to spot which Tol protein are more implicated in the interaction with colicin A as it is translocated to its target.

Keywords: K+ efflux, Colicin A, Tol-proteins, E. coli

Procedia PDF Downloads 406

Authors: A. Knezović

Abstract:

21st century has transformed the labor market landscape in a way of posing new and different demands on university graduates as well as university lecturers, which means that the knowledge and academic skills students acquire in the course of their studies should be applicable and transferable from the higher education context to their future professional careers. Given the context of the Languages for Specific Purposes (LSP) classroom, the teachers’ objective is not only to teach the language itself, but also to prepare students to use that language as a medium to develop generic skills and competences. These include media and information literacy, critical and creative thinking, problem-solving and analytical skills, effective written and oral communication, as well as collaborative work and social skills, all of which are necessary to make university graduates more competitive in everyday professional environments. On the other hand, due to limitations of time and large numbers of students in classes, the frequently topic-centered syllabus of LSP courses places considerable focus on acquiring the subject matter and specialist vocabulary instead of sufficient development of skills and competences required by students’ prospective employers. This paper intends to explore some of those issues as viewed both by LSP lecturers and by business professionals in their respective surveys. The surveys were conducted among more than 50 LSP lecturers at higher education institutions in Croatia, more than 40 HR professionals and more than 60 university graduates with degrees in economics and/or business working in management positions in mainly large and medium-sized companies in Croatia. Various elements of LSP course content have been taken into consideration in this research, including reading and listening comprehension of specialist texts, acquisition of specialist vocabulary and grammatical structures, as well as presentation and negotiation skills. The ability to hold meetings, conduct business correspondence, write reports, academic texts, case studies and take part in debates were also taken into consideration, as well as informal business communication, business etiquette and core courses delivered in a foreign language. The results of the surveys conducted among LSP lecturers will be analyzed with reference to what extent those elements are included in their courses and how consistently and thoroughly they are evaluated according to their course requirements. Their opinions will be compared to the results of the surveys conducted among professionals from a range of industries in Croatia so as to examine how useful and important they perceive the same elements of the LSP course content in their working environments. Such comparative analysis will thus show to what extent the syllabi of LSP courses meet the demands of the employment market when it comes to the students’ language skills and competences, as well as transferable skills. Finally, the findings will also be compared to the observations based on practical teaching experience and the relevant sources that have been used in this research. In conclusion, the ideas and observations in this paper are merely open-ended questions that do not have conclusive answers, but might prompt LSP lecturers to re-evaluate the content and objectives of their course syllabi.

Keywords: languages for specific purposes (LSP), language skills, topic-centred syllabus, transferable skills

Procedia PDF Downloads 305

Authors: Babak Azari, Afshin Pourahmad, Babak Sadeghi, Masuod Mokhtari

Abstract:

In this work, Equisetnm arvense plant extract was used for preparing amorphous SiO₂. For preparing of SiO₂/zeolitic imidazolate framework-8 (ZIF-8) nanocomposite by solvothermal method, the synthesized SiO₂ was added to the synthesis mixture ZIF-8. The nanocomposite was characterized using a range of techniques. The photocatalytic activity of SiO₂/ZIF-8 was investigated systematically by degrading crystal violet as a cationic dye under Ultraviolet light irradiation. Among synthesized samples (SiO₂, ZIF-8 and SiO₂/ZIF-8), the SiO₂/ZIF-8 exhibited the highest photocatalytic activity and improved stability compared to pure SiO₂ and ZIF-8. As evidenced by Scanning Electron Microscopy and Transmission electron microscopy images, ZIF-8 particles without aggregation are located over SiO₂. The SiO₂ not only provides structured support for ZIF-8 but also prevents the aggregation of ZIF-8 Metal-organic framework in comparison to the isolated ZIF-8. The superior activity of this photocatalyst was attributed to the synergistic effects from SiO₂ owing to (I) an electron acceptor (from ZIF-8) and an electron donor (to O₂ molecules), (II) preventing recombination of electron-hole in ZIF-8, and (III) maximum interfacial contact ZIF-8 with the SiO₂ surface without aggregation or prevent the accumulation of ZIF-8. The results demonstrate that holes (h+) and •O₂- are primary reactive species involved in the photocatalytic oxidation process. Moreover, the SiO₂/ZIF-8 photocatalyst did not show any obvious loss of photocatalytic activity during five-cycle tests, which indicates that the heterostructured photocatalyst was highly stable and could be used repeatedly.

Keywords: nano, zeolit, potocatalist, nanocomposite

Procedia PDF Downloads 75

Authors: Tingirtu Gebretsadik

Abstract:

This study aimed at explaining factors behind the ever increasing individualization over pastoral commons land and assesses the implication of the current change in property-ownership and land use system on the livelihoods of the Guji agro-pastoral system. Thus, three kebeles of Ana Sora woreda were selected for they conventionally appear to accommodate farming, pastoral and agro-pastoral systems. The survey method was employed to gather information on the major socio-economic condition of households. In-depth interviews and focus group discussions were also held in all the three kebele. The empirical results were interpreted by integrating institutional, livelihood and adaptation frameworks. In this study individualization of ownership of pastoral commons manifested in the form of fenced closures is on the rise among the Guji and it has been adopted as the outcome of a long run process. Factors related to ecology and rangeland degradation, socio-economic changes, land registration and certification has allowed the increasing engagement in fencing commons grazing land for individual use. Consequently, the Guji pastoral system of production demonstrated a declining trend, and are adapting to alternative livelihood strategies. Moreover, farming and other developments have facilitated pastoral land losses and land use claims and tenure ambiguities.

Keywords: land tenure, traditional institutions, property rights, fenced plots

Procedia PDF Downloads 208

Authors: Erdem Elibol, Musa Cadırcı, Nedim Tutkun

Abstract:

Recently, colloidal quantum dots (CQDs) have drawn increasing attention due to their unique size tunability, which makes them potential candidates for numerous applications including photovoltaic, LEDs, and imaging. However, the main challenge to exploit CQDs properly is that there has not been an effective method to produce them with highly crystalline form and narrow size dispersion. Hot injection method is one of the widely used techniques to produce high-quality nanoparticles. In this method, the key parameter is to reduce the time for injection of the precursors into each other, which yields fast and constant nucleation rate and hence to highly monodisperse QDs. In conventional hot injection method, the injection of precursors is carried out using standard lab syringes with long needles. However, this technique is relatively slow and thus will result in poor optical properties in QDs. In this work, highly luminescent CdTe QDs were synthesised by transferring hot precursors into each other using cannula method. Unlike regular syringe technique, with the help of high pressure difference between two precursors’ flasks and wide cross-section of cannula, the hot cannulation process is too short which yields narrow size distribution and high quantum yield of CdTe QDs. Here QDs with full width half maximum (FWHM) of 28 nm was achieved. In addition, the photoluminescence quantum yield of our samples was measured to be about 21 ± 0.9 which is at least twice the previous record values for CdTe QDs wherein syringe was used to transfer precursors.

Keywords: CdTe, hot injection method, luminescent, quantum dots

Procedia PDF Downloads 315

Authors: Jiajia Yao, Guanlin Wu, Fang Liu, Junshuai Xue, Yue Hao

Abstract:

This study reports on the epitaxial growth of a GaN-based resonant tunneling diode (RTD) structure with stable and repeatable double negative differential resistance (NDR) characteristics at room temperature on a c-plane GaN-on-sapphire template using plasma-assisted molecular beam epitaxy (PA-MBE) technology. In this structure, two independent AlN/GaN RTDs are epitaxially connected in series in the vertical growth direction through a silicon-doped GaN layer. As the collector electrode bias voltage increases, the two RTDs respectively align the ground state energy level in the quantum well with the 2DEG energy level in the emitter accumulation well to achieve quantum resonant tunneling and then reach the negative differential resistance (NDR) region. The two NDR regions exhibit similar peak current densities and peak-to-valley current ratios, which are 230 kA/cm² and 249 kA/cm², 1.33 and 1.38, respectively, for a device with a collector electrode mesa diameter of 1 µm. The consistency of the NDR is much higher than the results of on-chip discrete RTD device interconnection, resulting from the smaller chip area, fewer interconnect parasitic parameters, and less process complexity. The methods and results presented in this paper show the brilliant prospects of GaN RTDs in the development of multi-value logic digital circuits.

Keywords: MBE, AlN/GaN, RTDs, double NDR

Procedia PDF Downloads 59

Authors: Kuo-Cheng Liu

Abstract:

In the latest research efforts, the structures of the image in the spatial domain have been successfully analyzed and proved to deduce the visual masking for accurately estimating the visibility thresholds of the image. If the structural properties of the video sequence in the temporal domain are taken into account to estimate the temporal masking, the improvement and enhancement of the as-sessing spatio-temporal visibility thresholds are reasonably expected. In this paper, the temporal characteristics of human perception to the change in block structures on the time axis are analyzed. The temporal characteristics of human perception are represented in terms of the significant variation in block structures for the analysis of human visual system (HVS). Herein, the block structure in each frame is computed by combined the pattern masking and the contrast masking simultaneously. The contrast masking always overestimates the visibility thresholds of edge regions and underestimates that of texture regions, while the pattern masking is weak on a uniform background and is strong on the complex background with spatial patterns. Under considering the significant variation of block structures between successive frames, we extend the block structures of images in the spatial domain to that of video sequences in the temporal domain to analyze the relation between the inter-frame variation of structures and the temporal masking. Meanwhile, the subjective viewing test and the fair rating process are designed to evaluate the consistency of the temporal characteristics with the HVS under a specified viewing condition.

Keywords: temporal characteristic, block structure, pattern masking, contrast masking

Procedia PDF Downloads 407

Authors: Rosy Saikia, Krishna Barua

Abstract:

The evolution of visual art can be traced back from “pre-historic” humans, from the age of Paleolithic, Neolithic, and Metal Age. Mesopotamians and the Egyptians were the pioneers of art, in the first period of history. But the field of art first flourished in the west during the Renaissance. Since then, art represents a continuous yet varied tradition till present day. Until the early 19th century art focused chiefly on representational, religious and classical motifs, but gradually art became more abstract and conceptual approaches gained popularity. Rainer Maria Rilke (1875-1926) was one of the leading poets cum art critic of European modernism. This paper addresses the relationship between Rilke's poetry and visual art, which involves an intimate transference of aesthetic means and definitions of form in the creative process of writing. Rilke’s connection with Auguste Rodin made him learn that a person who can “see” things could realize the beauty of a “thing” and could subsequently write. To “see” the “thing” or “object” rather than representing emotion was considered as more important by Rodin and that was the way he cracked the old aesthetic mould. Rilke himself agreed that his correspondence with the artists made him acquainted nothing but a new way of seeing. Rilke admitted to the constant reference to the Bible, the books of the Danish poet Jens Peter Jacobsen and Auguste Rodin, who all had given him the experience of the essence of creativity, its depths and eternity. Rilke’s association with philosophers such as Nietzhche and artists, starting from Worpweders and Rodin to Cezanne’s paintings, made him almost an apprentice in visual art.

Keywords: seeing, gaze, aesthetic, beauty, visual art, Rilke

Procedia PDF Downloads 494

Authors: Ahmad Alazemi, M. Sherif El-Eskandrany, Mohamad Kishk, Thanyan AlOnaizi, Ahmad Alduweesh, Shorouq Abdullaleel

Abstract:

Arc melting technique followed by top-down approach, using a high-energy ball milling technique were employed to synthesize nanocrystalline of Cu50(Zr50-xNix)50 (x = 0, 10, 20 and 30 at.%) powder particles. The end-products of the alloy powders obtained after 50 h of the ball milling time were uniform in composition and had spherical-like morphology with an average particle size of 0.75 µm in diameter. The powders, which consisted of nanocrystalline grains with an average grain size of 10 nm in diameter, were used as feedstock materials for double face coating of stainless (SUS304) sheets, using cold spraying process. The coating materials enjoyed nanocrystalline structure and uniform composition. Biofilms were grown on 20-mm2 SUS304 sheets coated coupons inoculated with 1.5 × 108 CFU ml−1 E. coli. Significant biofilm inhibition was recorded in the nanoparticles coated coupons in comparison to non-coated SUS304 coupon. In conclusion, this study demonstrates that formation of biofilms can be significantly inhibited by Cu-based alloys especially in case of high (Ni) content. The inhibition of biofilm formation by nanocrystalline powders of Cu-based provides a practical approach to achieve the inhibition of biofilms formed by an emerging pathogen.

Keywords: biofilm, Cu, E.coli, FE-HRTEM/EDS, nanomaterials, nanocrystalline

Procedia PDF Downloads 415

Authors: Jesus Kombaya, Nadia Hamani, Lyes Kermad

Abstract:

The preservation of a company’s place on the market in such aggressive competition is becoming a survival challenge for manufacturers. In this context, survivors are only those who succeed to satisfy their customers’ needs as quickly as possible. The production system should be endowed with a certain level of flexibility to eliminate or reduce the rigidity of the production systems in order to facilitate the conversion and/or the change of system’s features to produce different products. Therefore, it is essential to guarantee the quality, the speed and the flexibility to survive in this competition. According to literature, this adaptability is referred to as the notion of "change". Indeed, companies are trying to establish a more flexible and agile manufacturing system through several reconfiguration actions. Reconfiguration contributes to the extension of the manufacturing system life cycle by modifying its physical, organizational and computer characteristics according to the changing market conditions. Reconfigurability is characterized by six key elements that are: modularity, integrability, diagnosability, convertibility, scalability and customization. In order to control the production systems, it is essential for manufacturers to make good use of this capability in order to be sure that the system has an optimal and adapted level of reconfigurability that allows it to produce in accordance with the set requirements. This document develops a measure of customization of reconfigurable production systems. These measures do not only impact the production system but also impact the product design and the process design, which can therefore serve as a guide for the customization of manufactured product. A case study is presented to show the use of the proposed approach.

Keywords: reconfigurable manufacturing systems, customization, measure, flexibility

Procedia PDF Downloads 123

Authors: Asmaa Selim, Peter Mizsey

Abstract:

Bio-ethanol is considered of higher potential as a green renewable energy source owing to its environmental benefits and its high efficiency. In the present study, silver nanoparticles were in-situ generated in a poly (vinyl alcohol) in order to improve its potentials for pervaporation of ethanol-water mixture using solution-casting. Effect of silver content on the pervaporation separation index and the enrichment factor of the membrane at 15 percentage mass water at 40ᵒC was reported. Pervaporation data for nanocomposite membranes showed around 100% increase in the water permeance values while the intrinsic selectivity decreased. The water permeances of origin crosslinked PVA membrane, and the 2.5% silver loaded PVA membrane are 26.65 and 70.45 (g/m².kPa.h) respectively. The values of total flux and water flux are closed to each other, indicating that membranes could be effectively used to break the azeotropic point of ethanol-water. Effect of temperature on the pervaporation performance, permeation parameter and diffusion coefficient of both water and ethanol was discussed. The negative heat of sorption ∆Hs values calculated on the basis of the estimated Arrhenius activation energy values indicating that the sorption process was controlled by Langmuir’s mode. The overall results showed that the membrane containing 0.5 mass percentage of Ag salt exhibited excellent PV performance.

Keywords: bio-ethanol, diffusion coefficient, nanocomposite, pervaporation, poly (vinyl alcohol), silver nanoparticles

Procedia PDF Downloads 165

Authors: Javad Jozaei, Rob G. Bell, Paula Blackett, Scott A. Stephens

Abstract:

In the last few decades, Social Vulnerability Assessment (SVA) has been a favoured means in evaluating the susceptibility of social systems to drivers of change, including climate change and natural disasters. However, the application of SVA to inform responsive and practical strategies to deal with uncertain climate change impacts has always been challenging, and typically agencies resort back to conventional risk/vulnerability assessment. These challenges include complex nature of social vulnerability concepts which influence its applicability, complications in identifying and measuring social vulnerability determinants, the transitory social dynamics in a changing environment, and unpredictability of the scenarios of change that impacts the regime of vulnerability (including contention of when these impacts might emerge). Research suggests that the conventional quantitative approaches in SVA could not appropriately address these problems; hence, the outcomes could potentially be misleading and not fit for addressing the ongoing uncertain rise in risk. The second phase of New Zealand’s Resilience to Nature’s Challenges (RNC2) is developing a forward-looking vulnerability assessment framework and methodology that informs the decision-making and policy development in dealing with the changing coastal systems and accounts for complex dynamics of New Zealand’s coastal systems (including socio-economic, environmental and cultural). Also, RNC2 requires the new methodology to consider plausible drivers of incremental and unknowable changes, create mechanisms to enhance social and community resilience; and fits the New Zealand’s multi-layer governance system. This paper aims to analyse the conventional approaches and methodologies in SVA and offer recommendations for more responsive approaches that inform adaptive decision-making and policy development in practice. The research adopts a qualitative research design to examine different aspects of the conventional SVA processes, and the methods to achieve the research objectives include a systematic review of the literature and case study methods. We found that the conventional quantitative, reductionist and deterministic mindset in the SVA processes -with a focus the impacts of rapid stressors (i.e. tsunamis, floods)- show some deficiencies to account for complex dynamics of social-ecological systems (SES), and the uncertain, long-term impacts of incremental drivers. The paper will focus on addressing the links between resilience and vulnerability; and suggests how resilience theory and its underpinning notions such as the adaptive cycle, panarchy, and system transformability could address these issues, therefore, influence the perception of vulnerability regime and its assessment processes. In this regard, it will be argued that how a shift of paradigm from ‘specific resilience’, which focuses on adaptive capacity associated with the notion of ‘bouncing back’, to ‘general resilience’, which accounts for system transformability, regime shift, ‘bouncing forward’, can deliver more effective strategies in an era characterised by ongoing change and deep uncertainty.

Keywords: complexity, social vulnerability, resilience, transformation, uncertain risks

Procedia PDF Downloads 93

Authors: Kun Liang Ang, Eng Toon Saw, Wei He, Xuecheng Dong, Seeram Ramakrishna

Abstract:

Ester solvents are widely used in pharmaceutical, printing and flavor industry due to their good miscibility, low toxicity, and high volatility. Through pervaporation, these ester solvents can be recovered from industrial wastewater. While metal-doped silicalite 1 zeolite membranes are commonly used in organic solvent recovery in the pervaporation process, these ceramic membranes suffer from low membrane permeation flux, mainly due to the high thickness of the metal-doped zeolite membrane. Herein, a simple method of fabricating an ultrathin tin-silicalite 1 membrane supported on alumina tube is reported. This ultrathin membrane is able to achieve high permeation flux and separation factor for an ester in a diluted aqueous solution. Nanosized tin-Silicalite 1 seeds which are smaller than 500nm has been formed through hydrothermal synthesis. The sn-Silicalite 1 seeds were then seeded onto alumina tube through dip coating, and the tin-Silicalite 1 membrane was then formed by hydrothermal synthesis in an autoclave through secondary growth method. Multiple membrane synthesis factors such as seed size, ceramic substrate surface pore size selection, and secondary growth conditions were studied for their effects on zeolite membrane growth. The microstructure, morphology and the membrane thickness of tin-Silicalite 1 zeolite membrane were examined. The membrane separation performance and stability will also be reported.

Keywords: ceramic membrane, pervaporation, solvent recovery, Sn-MFI zeolite

Procedia PDF Downloads 185

Authors: Chandrashekhar Bhat, Dilifa Jossley Noronha, Faber A. Saldana

Abstract:

Transportation of long turbine blades from one place to another is a difficult process. Hence a feasibility study of modularization of wind turbine blade was taken from structural standpoint through finite element analysis. Initially, a non-segmented blade is modeled and its structural behavior is evaluated to serve as reference. The resonant, static bending and fatigue tests are simulated in accordance with IEC61400-23 standard for comparison purpose. The non-segmented test blade is separated at suitable location based on trade off studies and the segments are joined with an innovative double strap bonded joint configuration. The adhesive joint is modeled by adopting cohesive zone modeling approach in ANSYS. The developed blade model is analyzed for its structural response through simulation. Performances of both the blades are found to be similar, which indicates that, efficient segmentation of the long blade is possible which facilitates easy transportation of the blades and on site reassembling. The location selected for segmentation and adopted joint configuration has resulted in an efficient segmented blade model which proves the methodology adopted for segmentation was quite effective. The developed segmented blade appears to be the viable alternative considering its structural response specifically in fatigue within considered assumptions.

Keywords: modularization, fatigue, cohesive zone modeling, wind turbine blade

Procedia PDF Downloads 444

Authors: Bhavya Tripathi, Bhupendra Kumar Sharma

Abstract:

In blood, the concentration of red blood cell varies with the arterial diameter. In the case of narrow arteries, red blood cells concentrate around the center of the artery and there exists a cell-free plasma layer near the arterial wall due to Fahraeus-Lindqvist effect. Due to non- uniformity of the fluid in the narrow arteries, it is preferable to consider the two-phase model of the blood flow. In the present article, coupled nonlinear differential equations have been developed for momentum, energy and concentration of two phase model of the blood flow assuming the Newtonian fluid in both central core and cell free plasma layer and the exact solutions have been found for the problem. For having an adequate insight into the stenosed arterial two-phase blood flow, major components of the flow as flow resistance, total flow rate, and wall shear stress have been estimated for different values of magnetic and radiation parameter. Results show that the increase in the effects of magnetic field decreases the velocity of both cores as well as plasma regions. This result can be helpful to control the blood flow in narrow arteries during surgical process. Temperature of core as well plasma regions decrease as value of radiation parameter increases. The present result is implemented in the form of radiation therapy which is very helpful for cancer patients.

Keywords: two phase blood flow, radiation, magnetohydrodynamics (MHD), stenosis

Procedia PDF Downloads 197

Authors: Popoola M. Oyenola

Abstract:

Concrete plays the important role and a huge percentage of concrete is being utilized in every construction practices. Natural river sand is one of the major ingredients of concrete, is becoming expensive due to excessive cost of accessibility from sources. Also large scale depletion of sources creates environmental problems. Therefore, there is a need of economic alternative materials. Quarry dust is a waste obtained during quarrying process. It has been rampantly used in different construction practices and could be used as an effective fine aggregate instead of river sand. Partial and total replacement of fine aggregate in conventional concrete with quarry dust has been empirically conducted with the view to examining primarily the compressive strength of the resulting composite and possible total utilization of quarry dust as fine aggregate in the production of medium grade concrete. The results of the study showed that its specific gravity, porosity and water absorption showed satisfactory performance. The percentage replacement of natural river sand with quarry dust for a designed strength of 25N/mm2 varied at intervals of 10% up to a maximum value of 100%. A total of 132 cubes of 150 x 150 x 150mm were cast and tested at 7, 14 and 28 days of hydration. Compressive strength increases with curing age in all the mixes. Compressive strength decreases with increase in percentage of quarry dust. Generally the compressive strength of concrete incorporating quarry dust attained strength of 22.47 N/mm2 after 28 days which makes it a suitable aggregate for the production medium grade concrete.

Keywords: quarry dust, concrete, aggregates, compressive strength

Procedia PDF Downloads 240

Authors: Dalia Salem, Detlef Schulz

Abstract:

As Germany pursues its ambitious plan towards a power system based on renewable energy sources, the necessity to establish steady, robust microgrids becomes more evident. Inside the microgrid, there is at least one grid-forming inverter responsible for generating the coupling voltage and stabilizing the system frequency within the standardized accepted limits when the microgrid is forced to operate as a stand-alone power system. Grid-forming control for distributed inverters is required to enable steady control of a low-inertia power system. In this paper, a designed droop control technique is tested at the controller of an inverter as a component of a hardware test bed to understand the microgrid behavior in two modes of operation: i) grid-connected and ii) operating in islanding mode. This droop technique includes many current and voltage inner control loops, where the Q-V and P-f droop provide the required terminal output voltage and frequency. The technique is tested first in a simulation model of the inverter in MATLAB/SIMULINK, and the results are compared to the results of the hardware laboratory test. The results of this experiment illuminate the pivotal role of the grid-forming inverter in facilitating microgrid resilience during grid disconnection events and how microgrids could provide the functionality formerly provided by synchronous machinery, such as the black start process.

Keywords: microgrid, grid-forming inverters, droop-control, islanding-operation

Procedia PDF Downloads 64

Authors: Tsirekidze M., Aprasidze T.

Abstract:

Introduction: The problem of dissocial behavior is at the heart of the social sciences and psychiatry; however, it should be noted that its psychiatric aspect is little studied, and some issues of the problem are still controversial. This is complicated by the diversity of terminological concepts in defining “dissocial behavior”, “behavioral disorder”, “abnormal behavior”, “deviant behavior”, “delinquent behavior”, etc. In literature, there is no comprehensive definition of the essence of dissociative behavior. Numerous attempts to systematize dissociative disorders should also be considered unsatisfactory, which is primarily related to the lack of solid criteria for defining this group of disorders. According to the clinical classification, dissocial behavior is divided into psychotic and non-psychotic forms. Such differentiation is conditional in nature since it is not always possible to draw precise, clear distinctions between these forms, and in addition, there is a transition of a behavior disorder or so-called intermediate forms. One group of authors distinguishes two main forms of deviant behavior in terms of both theoretical and practical significance - non-pathological and pathological. In recent years, especially, the non-pathological form of behavior disorder has become topical. It refers to a large group of forms of deviant behavior, the emergence of which is associated with psychologically full-fledged reactions of children and adolescents to stressful situations and extreme conditions. According to the authors, its concept is understandable-it is difficult to draw a line between psychologically understandable reactions and psychogenically induced reactive states. In addition, the concept of "normal" child and adolescent is, to some extent, a vague concept, as in medicine, any definition of the norm. From a practical (more precisely, pragmatic) point of view, the term "abnormal behavioral disorder" undoubtedly makes sense, especially for the purpose of forensic psychiatric examination. Non-pathological deviation mainly includes transient situational reactions, microsocial-pedagogical backwardness, and character accentuation.Deviant behavior was predominantly manifested in a non-pathological form, which, in our opinion, is due to the difficult socio-economic situation of the country, moral-ethical deprivation, and expressed frustration. By itself, society is an indicator of deviation. Add to this situation complicated factors such as micro-social-pedagogical leave, unfavorable family environment, and parenting defects. Consideration is also given to the connection of acceptable deviation with the personal structural features of the adolescent. Aim: The topic of our discussion is the dissocial behavior of the non-psychotic register. Methods: We surveyed 120 adolescents with deviant behaviors. 61% of them were diagnosed with various neuropsychiatric disorders. Results: Abnormal forms of deviant behavior were observed in 13%, and non-pathological forms in -69%. A combination of non-pathological and pathological forms was present in 10% of cases. In the case of non-pathological deviation, microsocial-pedagogical acceptance was revealed in 62%, character accentuation in 22%; during the pathological forms, pathological reactions were observed in 21%, and abnormal formation of the person -21%. Conclusion: It should be emphasized that in case of any of the above defects, if the so-called family psychosis, and medical and pedagogical habilitation measures for the adolescent, it is quite possible to prevent the abnormal development of the child's personality, correct his character, regulate behavior and develop positive labor-social relations.

Keywords: dissocial personality, deviant behavior, dissocial, delinquent behavior

Procedia PDF Downloads 214

Authors: Sajid Shah, Yoshimitsu Uemura, Katsuki Kusakabe

Abstract:

Sol-gel derived hydrophobic silica membranes with pore sizes less than 1 nm are quite attractive for gas separation in a wide range of temperatures. A nano-structured hydrophobic membrane was prepared by sol-gel technique on a porous α–Al₂O₃ tubular support with yttria stabilized zirconia (YSZ) as an intermediate layer. Bistriethoxysilylethane (BTESE) derived sol was modified by adding phenyltriethoxysilylethane (PhTES) as an organic template. Six times dip coated modified silica membrane having a thickness of about 782 nm was characterized by field emission scanning electron microscopy. Thermogravimetric analysis, together along contact angle and Fourier transform infrared spectroscopy, showed that hydrophobic properties were improved by increasing the PhTES content. The contact angle of water droplet increased from 37° for pure to 111.5° for the modified membrane. The permeance of single gas H₂ was higher than H₂:CO₂ ratio of 75:25 binary feed mixtures. However, the permeance of H₂ for 60:40 H₂:CO₂ was found lower than single and binary mixture 75:25 H₂:CO₂. The binary selectivity values for 75:25 H₂:CO₂ were 24.75, 44, and 57, respectively. Selectivity had an inverse relation with PhTES content. Hydrophobicity properties were improved by increasing PhTES content in the silica matrix. The system exhibits proper three layers adhesion or integration, and smoothness. Membrane system suitable in steam environment and high-temperature separation. It was concluded that the hydrophobic silica membrane is highly promising for the separation of H₂/CO₂ mixture from various H₂-containing process streams.

Keywords: gas separation, hydrophobic properties, silica membrane, sol–gel method

Procedia PDF Downloads 119

Authors: Duncan K. Espenshade

Abstract:

Scholars have established expectations regarding how the political and economic interests of a country's people and elites can influence its migration policies. Most of the scholarship exploring the adoption of migration policies focuses on the developed world, focusing on the cultural, political, and economic influences that drive restrictive policies in developed countries. However, despite the scholarly focus on migration policies in developed countries, most internationally displaced people reside in developing countries. Furthermore, while the political and economic factors that influence migration policy in developed countries are likely at play in developing states, developing states also face unique hurdles to policy formation not present in developed states. Namely, this article explores how state capacity, or in this context, a state's de facto ability to restrict or absorb migration inflows, influences the adoption of migration policies in developing countries. Using Cox-Proportional hazard models and recently introduced data on asylum policies in developing countries, this research finds that having a greater ability to restrict migration flows is associated with a reduced likelihood of adopting liberal asylum policies. Future extensions of this project will explore the adoption of asylum policies as a two-stage process, in which the available decision set of political actors is first constrained by a state's restrictive and absorptive capacity in the first stage, with the political, economic, and cultural factors influencing the policy adopted in the second stage.

Keywords: state capacity, international relations, foreign policy, migration

Procedia PDF Downloads 100

Authors: Lynne Soon-Chean Park

Abstract:

Critical Realism (CR) has emerged as an alternative to both the positivist and constructivist perspectives that have long dominated social work research. By unpacking the epistemic weakness of two dogmatic perspectives, CR provides a useful philosophical approach that incorporates the ontological objectivist and subjectivist stance. The CR perspective suggests an alternative approach for social work researchers who have long been looking to engage in the complex interplay between perceived reality at the empirical level and the objective reality that lies behind the empirical event as a causal mechanism. However, despite the usefulness of CR in informing social work research, little practical guidance is available about how CR can inform methodological considerations in social work research studies. This presentation aims to provide a detailed description of CR-informed thematic analysis by drawing examples from a social work doctoral research of Korean migrants’ experiences and understanding of trust associated with their settlement experience in New Zealand. Because of its theoretical flexibility and accessibility as a qualitative analysis method, thematic analysis can be applied as a method that works both to search for the demi-regularities of the collected data and to identify the causal mechanisms that lay behind the empirical data. In so doing, this presentation seeks to provide a concrete and detailed exemplar for social work researchers wishing to employ CR in their qualitative thematic analysis process.

Keywords: critical Realism, data analysis, epistemology, research methodology, social work research, thematic analysis

Procedia PDF Downloads 209

Authors: C. J. Coetzee, E. Horn

Abstract:

One of the main challenges in using the Discrete Element Method (DEM) is to specify the correct input parameter values. In general, the models are sensitive to the input parameter values and accurate results can only be achieved if the correct values are specified. For the linear contact model, micro-parameters such as the particle density, stiffness, coefficient of friction, as well as the particle size and shape distributions are required. There is a need for a procedure to accurately calibrate these parameters before any attempt can be made to accurately model a complete bulk materials handling system. Since DEM is often used to model applications in the mining and quarrying industries, a calibration procedure was developed for materials that consist of relatively large (up to 40 mm in size) particles. A coarse crushed aggregate was used as the test material. Using a specially designed large shear box with a diameter of 590 mm, the confined Young’s modulus (bulk stiffness) and internal friction angle of the material were measured by means of the confined compression test and the direct shear test respectively. DEM models of the experimental setup were developed and the input parameter values were varied iteratively until a close correlation between the experimental and numerical results was achieved. The calibration process was validated by modelling the pull-out of an anchor from a bed of material. The model results compared well with experimental measurement.

Keywords: Discrete Element Method (DEM), calibration, shear box, anchor pull-out

Procedia PDF Downloads 289

Authors: Peikun Zhang, Chunhua Cui

Abstract:

Photoelectrochemical (PEC) water splitting provides a promising pathway to convert solar energy into renewable fuels. However, the main and seemingly insurmountable obstacle is that the sluggish kinetics of oxygen evolution reaction (OER) severely jeopardizes the overall efficiency, thus exploring highly active, stable, and appreciable catalysts is urgently requested. Herein a competitive coordination strategy was demonstrated to form a reversible hybrid homo-heterogeneous catalyst for efficient OER in alkaline media. The dynamic process involves an in-situ anchoring of soluble nickel–bipyridine pre-catalyst to a conductive substrate under OER and a re-dissolution course under open circuit potential, induced by the competitive coordination between nickel–bipyridine and nickel-hydroxyls. This catalyst allows to elaborately self-modulate a charge-transfer layer thickness upon the catalytic on-off operation, which affords substantially increased active sites, yet remains light transparency, and sustains the stability of over 200 hours of continuous operation. The integration of this catalyst with exemplified state-of-the-art Ni-sputtered Si photoanode can facilitate a ~250 mV cathodic shift at a current density of 20 mA cm-2. This finding helps the understanding of catalyst from a “dynamic” perspective, which represents a viable alternative to address remaining hurdles toward solar-driven water oxidation.

Keywords: molecular catalyst, oxygen evolution reaction, solar energy, transition metal complex, water splitting

Procedia PDF Downloads 121

Authors: Chevonne Reynolds, Res Altwegg, Andrew Balmford, Claire N. Spottiswoode

Abstract:

Modern agriculture has revolutionised the planet’s capacity to support humans, yet has simultaneously had a greater negative impact on biodiversity than any other human activity. Balancing the demand for food with the conservation of biodiversity is one of the most pressing issues of our time. Biodiversity-friendly farming (‘land sharing’), or alternatively, separation of conservation and production activities (‘land sparing’), are proposed as two strategies for mediating the trade-off between agriculture and biodiversity. However, there is much debate regarding the efficacy of each strategy, as this trade-off has typically been addressed by short term studies at fine spatial scales. These studies ignore processes that are relevant to biodiversity at larger scales, such as meta-population dynamics and landscape connectivity. Therefore, to better understand species response to agricultural land-use and provide evidence to underpin the planning of better production landscapes, we need to determine the merits of each strategy at larger scales. In South Africa, a remarkable citizen science project - the South African Bird Atlas Project 2 (SABAP2) – collates an extensive dataset describing the occurrence of birds at a 5-min by 5-min grid cell resolution. We use these data, along with fine-resolution data on agricultural land-use, to determine which strategy optimises the agriculture-biodiversity trade-off in a southern African context, and at a spatial scale never considered before. To empirically test this trade-off, we model bird species population density, derived for each 5-min grid cell by Royle-Nicols single-species occupancy modelling, against both the amount and configuration of different types of agricultural production in the same 5-min grid cell. In using both production amount and configuration, we can show not only how species population densities react to changes in yield, but also describe the production landscape patterns most conducive to conservation. Furthermore, the extent of both the SABAP2 and land-cover datasets allows us to test this trade-off across multiple regions to determine if bird populations respond in a consistent way and whether results can be extrapolated to other landscapes. We tested the land sparing/sharing trade-off for 281 bird species across three different biomes in South Africa. Overall, a higher proportion of species are classified as losers, and would benefit from land sparing. However, this proportion of loser-sparers is not consistent and varies across biomes and the different types of agricultural production. This is most likely because of differences in the intensity of agricultural land-use and the interactions between the differing types of natural vegetation and agriculture. Interestingly, we observe a higher number of species that benefit from agriculture than anticipated, suggesting that agriculture is a legitimate resource for certain bird species. Our results support those seen at smaller scales and across vastly different agricultural systems, that land sparing benefits the most species. However, our analysis suggests that land sparing needs to be implemented at spatial scales much larger than previously considered. Species persistence in agricultural landscapes will require the conservation of large tracts of land, and is an important consideration in developing countries, which are undergoing rapid agricultural development.

Keywords: agriculture, birds, land sharing, land sparing

Procedia PDF Downloads 205

Authors: Thanida Sritangthong, Suksun Amornraksa

Abstract:

By-product upgrading is crucial in hydrocarbon industries as it can increase overall profit margin of the business. Microwave-assisted pyrolysis is relatively new technique which induces heat directly to raw materials. This results in a more energy saving and more energy-efficient process. It is also a promising method to enhance and accelerate chemical reactions, thus reducing the pyrolysis reaction time and increasing the quality of value-added products from different kinds of feedstocks. In this study, upgrading opportunity of fuel oil by-product from an olefins plant is investigated by means of microwave pyrolysis. The experiment was conducted in a lab-scale quartz reactor placed inside a 1,100 watts household microwave oven. Operating temperature was varied from 500 to 900C to observe the consequence on the quality of pyrolysis products. Several microwave receptors i.e. activated carbon, silicon carbide (SiC) and copper oxide (CuO) were used as a material to enhance the heating and reaction in the reactor. The effect of residence time was determined by adjusting flow rate of N2 carrier gas. The chemical composition and product yield were analyzed by using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The results showed that hydrogen, methane, ethylene, and ethane were obtained as the main gaseous products from all operating temperatures while the main liquid products were alkane, cycloalkane and polycyclic aromatic groups. The results indicated that microwave pyrolysis has a potential to upgrade low value hydrocarbons to high value products.

Keywords: fuel oil, heavy hydrocarbons, microwave pyrolysis, pyrolysis

Procedia PDF Downloads 312

Authors: Abdel Khalek Selim, Safaa Mahmoud

Abstract:

Experiments were designed to study nitrogen loss through leaching in soil columns treated with different nitrogen sources and elemental sulfur. The soil material (3 kg alluvial or calcareous soil) were packed in Plexiglas columns (10 cm diameter). The soil columns were treated with 2 g N in the form of Ca(NO3)2, urea, urea + inhibitor (Nitrapyrin), another set of these treatments was prepared to add elemental sulfur. During incubation period, leaching was performed by applying a volume of water that allows the percolation of 250-ml water throughout the soil column. The leachates were analyzed for NH4-N and N03-N. After 10 weeks, soil columns were cut into four equal segments and analyzed for ammonium, nitrate, and total nitrogen. Results indicated the following: Ca(NO3)2 treatment showed a rapid NO3 leaching, especially in the first 3 weeks, in both clay and calcareous soils. This means that soil texture did not play any role in this respect. Sulfur addition also did not affect the rate of NO3 leaching. In urea treatment, there was a steady increase of NH4- and NO3–N from one leachate to another. Addition of sulfur with urea slowed down the nitrification process and decreased N losses. Clay soil contained residual N much more than calcareous soil. Almost one-third of added nitrogen might have been immobilized by soil microorganisms or lost through other loss paths. Nitrification inhibitor can play a role in preserving added nitrogen from being lost through leaching. Combining the inhibitor with elemental sulfur may help to stabilize certain preferred ratio of NH4 to NO3 in the soil for the benefit of the growing plants.

Keywords: alluvial soil, calcareous soil, elemental sulfur, nitrate leaching

Procedia PDF Downloads 312

Authors: Ana Maria De Azevedo

Abstract:

We are living a remarkable period, responsible for the thriving of the human population to unprecedented levels. Still, it is empirically obvious that sustaining such a huge population puts a tremendous pressure on our planet. Once Land resources grow scarcer, there is a mounting pressure to find alternatives to support basic human needs elsewhere. Occupying most of our planet, it’s therefore natural that, is not a so distant future, humankind look for such basic subsistence means at the Ocean. Thus, once the Ocean becomes essential to Human subsistence, it is predictable it's moving to the foreground of Geopolitics. Both future technologies and uses of the Ocean, as bidding for the exploration of its resources away from the natural territory of influence of a Country, are susceptible of raising the risk of conflict between traditional political adversaries and/or the dilemma of having to balance economic interests, with various security and defense concerns. Those empirical observations suggest the need to further research on this perspective shift of the main Geopolitical axis to the Ocean, the new sources of conflict that can result thereon, and how to address them. The author suggests a systematic analysis of this problematic, to attain a political and legal international consensus, namely on what concerns updating of the 'United Nations Convention on the Law of the Sea' of 10 December 1982, and/or its annexes. To proceed with the present research, the primary analysis was based on a quantitative observation, but reasoning thereon relied essentially on a qualitative process of prospective scenarios assessment.

Keywords: marine resources, ocean geopolitics, security and defense, sustainable development

Procedia PDF Downloads 151

Authors: B. Moaveni, S. Morovati

Abstract:

In recent years, increasing the usage of railway transportations especially in developing countries caused more attention to control systems railway vehicles. Consequently, designing and implementing the modern control systems to improve the operating performance of trains and locomotives become one of the main concerns of researches. Dynamic braking systems is an important safety system which controls the amount of braking torque generated by traction motors, to keep the adhesion coefficient between the wheel-sets and rail road in optimum bound. Adhesion force has an important role to control the braking distance and prevent the wheels from slipping during the braking process. Cascade control structure is one of the best control methods for the wide range of industrial plants in the presence of disturbances and errors. This paper presents cascade control structure based on two forward simple controllers with two feedback loops to control the slip ratio and braking torque. In this structure, the inner loop controls the angular velocity and the outer loop control the longitudinal velocity of the locomotive that its dynamic is slower than the dynamic of angular velocity. This control structure by controlling the torque of DC traction motors, tries to track the desired velocity profile to access the predefined braking distance and to control the slip ratio. Simulation results are employed to show the effectiveness of the introduced methodology in dynamic braking system.

Keywords: cascade control, dynamic braking system, DC traction motors, slip control

Procedia PDF Downloads 359